Production of alkali hydroxides



April 24, 1956 G. MILLER ET Al. 2,743,165

PRODUCTION OF ALKALI HYDROXIDES INVENTORS GEORGE MILLE/P CHASE GOD/:REV

April 24, 1956 G. MILLER ET Al.

PRODUCTION OF ALKALI HYDROXIDES 2 Sheets-Sheet 2 Filed Aug. 15, 1950 IIOVU@ 1kg NRE Q@ NNwN www www@ QNS

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` PRODUCTION or ALKALI HYDRoxrDEs George Miller, Barranquilla, Colombia, and Frank Chase Godfrey, Boston, Mass.

M l Application August 1s, 195o, seriaiNo. 119,574

9 claims. (cl. zs1s4)` This invention relates to the manufacture of alkali metal hydroxides, for instance sodium hydroxide, and more particularly to the production of'such alkali metal hydroxides in, commercial grades and quantities by ion exchange. For a description of the background of the commercial production of alkali metal hydroxides'particularly caustic soda and the need for cheaper methods of production reference' is made to the copending application of Godfrey Serial No. 153,219, yiiled March 3l, 1950,now abandoned. 4 l

' One of the great advantages of the present invention is that the high concentrations which can be obtained in the end products of the present ion exchange process eliminates the necessity of evaporator equipment, boilers and the like for further concentration ofthe end product thereby substantially reducingthe capital investment required for the commercial plant.

We have discovered that alkali metal hydroxides can be` produced in concentrated formlby ion exchange by using a concentrated hydroxide of either barium or strontium which, in turn may be produced as a precipitate and concentrated in solution by taking advantage of its property of variation of solubility with temperature.

o In the following description the present invention is illustrated by preferred examples selected from any possibilities .which the' invention makesappa'rent and the scope of the claims is not intended to be limited to the examples contained in the description and in the schematic drawings more clearly illustrating the process of which: Fig'l is a schematic diagram of a one' stagecation exchange process for concentrating sodium hydroxide according tothe invention; 4 n j Fig'. 2 2v is a schematic drawing of a three stage regeneration ion exchange process embodying the invention.

GENERAL DESCRIPTON An ion is the smallest particle into which a substance in solution can be divided and still retain its identity and ionization orrdivision into component positive ions or cations and negative ions or anions occurs when a composition is in solution. For each cation there is a corresponding anion thus, for instance, sodium hydroxide NaOH comprises molecules eachy formed with a positively charged sodium ion or cation Na-land a negatively charged hydroxyl ion or anion OH-. In solution these ions have the property of being able to separate or disassociate and to associate themselves withother oppositely charged ions from or in another substance or composition present in or in contact with the solution. This process is ion exchange and the other substance exchanges a similarly charged ion in return for the ion which becomes associated with it, which may associate itself with an oppositely charged ion of the first composition. This process is analogous to the exchange of partners between two couples on a dance floor.

An ion exchanger is any composition or substance which is capable of exchanging one of its ions either cation or anion for one of the similarly charged ions of the composition and solution which is passed through an in contact with the ion exchanger for convenience called the exchanger.

An exchanger for the purposes of this invention is fa mass or quantity of an insoluble or permanent material,

usually in a granulated pea, saddle or other relatively" divided form and lying in a batch or bed so arranged as in a tank 'that solutions can be passed through and in contact with it.

Generally speaking, any suitable cation exchangers may. be used in the process of our invention which are capable of exchange between the form having the ion of the alkali metal of the salt from which the hydroxide is to be duced and the barium or strontium form.

`The'recently developed synthetic exchangers from which may be selected vthose best for the particular process in-y volved according to readily available data are at present most satisfactory, for instance the sulphonated copolymers of phenol and formaldehyde and the likey which are available on the marketunder the trade name Amberlite such as the cation exchangers Amberlite IR-105," a

sulphonic acid type, Amberlite IRC-50 a carboxyl lacid Atype and Amberlite 120, a sulphonic acid type.

It will be understood that the ion exchangers, particularly the synthetic resin ion exchangers discussed are well known and that a suitable exchanger may be selected from among such readily available exchangers according to publicly available table data and their complicated chemical formulas and compositions for the most part need not be dealt with here. For our purposes the cation exchange materials maybe designated by R. Throughout the process of this invention a resin cation exchanger will be in the form of a metallic resinate, for instance a strontium resinate SrRz which is interchangeable in form as the process of cation exchange takes place with for instance the sodium form NaR.

The invention can` perhaps be best understood in general principle as follows:

lf a strong solution of strontium hydroxide Sr(OH)2| is passed through the sodium resinate NaR form of ex;

changer, the exchanger becomes strontium resinate SrRz" and concentrated end product sodium hydroxide NaOH is produced as eiiiuent in a iirst run throughthe exchanger. Then the strontium resinate SrRz form of exchanger may-l be regenerated back to the sodium form by passing in a second run a supply of sodium chloride NaCl throughy it, producing as exchanger etiiuent a mixture of strontium chloride SrC12 and sodium chloride NaCl. The supply of concentrated strontium hydroxide is produced by combining in any manner the strontium Sr++ ion from the strontium chloride exchanger effluent with a hydroxyl ion OH- obtained from any suitable hydroxide. The

strontium hydroxide may be produced in great quantity at low temperature whereby it is precipitated out as a solid and accumulated. Thereafter a small amounty of- As above mentioned strontium may be replaced by conbarium to form the precipitated hydroxide which is centrated for use in the production run.

Example 7.-0ne stage regeneration Fig. 1 illustrates the invention in a single stage regeneration process.

In the production or iirst run, concentrated solubilized strontium hydroxide'Sr(OH)2 is led through a line .1()v and into an exchanger tank 12 containing the sodium` The exchanger becomes;4

NaR form of ion exchanger. strontium resinate SrRa and concentrated sodium hydrox- Patente'd Apr. 24,'19'561" prof ing `:1r-supply ofsodium. chloride NaClthrough theline 10A thereby: producing as eiluent to ,the line-14Aa mixture of strontium chloride SrCl2 and sodium chloride NaCl in solution.

.The lattermixture -is treated laccordingto the process of .ouropending application Serial No. 171886,' filed August 5, `19,50, 4by feeding it from the `linel4A ina frstrrun iinto an exchange apparatusl containing resinl hydroxide RxOH form of anion exchanger. The exchanger rever-ts .to .a resin :chloride .formfRXCl andstrontiunrhydroxide Sr(OH)2 lis produced as -a solidfprecipitateuirrthe:` exchangerwith waste sodium chloride NaCl as ,euent 4throughfthe .line 18. A small amount .of hot water H2O isthentcd into the .exchanger ,tankrl through theline 19 .dissolviugthe strontium hydroxide prccipitateand regenerating ,the resin chloridefexchanger back to theresin` hydroxide formforming concentrated strontium chloride SrCla as euentfthroughthe line 20. The methodofconcentrating the strontium kchloride as described ,is Yoptional in thepresent inventionother suitable methodsbeing applicable. T he strontium chloride from Iline 20 is combined with copper ammoniumfhydroxide Cu(NH3)2(OH)z from the line 24 `to formva precipitate Ystrontium hydroxide Sr(OH)2 which is accumulated in apparatusrZZ. -Then a small amount of hot water is introduced through the line26 dissolving theprecipitateinto` a highly concentrated solution as efuent inthe line 28 from which it supplies the line 10 for the first` run in theapparatus 12. When the strontiurn chloride and .the copper ammonium hydroxide are reacted in the apparatuslz, copper` ammonium -chloride Cu(NI-I3)Cl2.is `a reaction `product in the line 30 from which, it ,may be combined with calcium hydroxide CaOH from` the line 32r in` reactionvapparatus `3 4 producing cop.- per hydroxide Cu(OH); .and ammonia intheline 36 which is recirculated to the line,24.

Thelpresent Yexamplebeing merely illustrative :the in vention is intended to cover anymeans for precipitating the.. strontium hydroxide or equivalent barium hydroxide for use inthe rst run through line 10 lin the exchange apparatus v12 of Fig.v l.

`The equations ,for the above reactions are as follows: (l) Sr(OH) 2.l-2NaR' ,:SrR2-l-2NaOH (2) y.ColdSrClz-l-NaCl-t Example 2,-Dsplacement of barium r strontumvby a coiriplexibleA metal electralite Fig, 2 illustrates analternative process according to the invention embodying a production run rand three regenerationrunsfincluding displacement ofythe bariumgor equivalent strontiumion witha complexible metalelectrolite.

Concentrated barium hydroxide in solution is introduced from the line 40 to a series of exchangerctanks 41, 42and 43 containing progressively exhausted sodium resinate NaR form of exchangerconnected in series by the lines 44 and 45 thereby producing concentratedy sodium hydroxide as end product eiuent kfrom the line 46.

As thc exchanger batches from the production series representedby' the tanks 41, `42 `and .43 become exhausted to the barium form they are moved successively tocanrst regeneration stage represented by tanks51, 52 and 53, connected in seriesby the lines `54 and v55 to which copperammonium'chloride Cu(-NH3)2Cl2 is introduced from the line 60\thereby reverting the `ex- 4 changer to the copper ammonium resinate 'Cu'(NH3)`2Rz form and producing barium chloride BaClz as eiuent in a line 61.

Tanks from the series 51-53 which became regenerated to the copper ammonium resinate form are moved successively to a second regeneration stage represented by` tanksY 64, 65 and 66 connected in series by lines 67 and 68. Calcium chloride CaClz in line 70 is passed through the tanks 64-66 regenerating them to a calciumv resinate CaRz form andproducing copper ammonium 4chloride Cu(NI-I3)2Clz in aline 7,1.

From the second stage of regeneration the tanks 64 to 66 are successively moved when regenerated to the calcium resinate form 'into a third stage of regeneration represented by the series of tanks 73, 74 and 75 connected in series by the lines 76, 77. Sodium chloride NaCl is introduced to the calcium resnate from the line producing calcium chloride CaClz as effluent from the` line v81and,reverting the exchanger` back to the-sodium .form NaR ready for `the production n11.r1:1'epre` sented by .the tanks -,41,V42iaud 43.

Thus, 4the displacement of the .selected alkaliuoea-rth metal from the alkaline earth metal resinate vion Aexchanger ,.and-the regeneration of theionexchauzertto the v original .alkali metalresinate is carried out sequentially ,in ,ai plurality of ion exchange runsfwhich ,include passing through the exchanger kan ionizablersalt pta metal other than the said alkali ear-th metal .to.pr.oduce theV eiuent containing the ionizable saltof theselected alkaline earth metal I'and 4thereafter. passing through the exchangerthcrionizable saltof the -desiredalkalimetal to regeneratethe exchanger to the alkali metal resinate form for the production run.

The copper ammonium chloride, in the line 71..is,re

acted in the usual manner with calcium hydroxide Ca(CH)2 fromia line85 in reaction apparatus 86 to form copper hydroxide Cu(OH2) eluentin a line 90f1'ee ammonia NH3 `in a line 91l and calcium chloride CaClz inv a ,-1ine` ,9,3, the latter recirculating back into the. calcium chloride supply line 70. Y

The copper-hydroxide Cu(OH)2 from theline 90 ,the free ammonia NH3 in the line 91 `and the kbar-lum chloride BaCl2 in the line 61 are reacted in the usual manner, in apparatus to precipitate Vbarium hydroxide -Ba(OH)f2 in the line 97 and,productcopper ammonia chloride Cu(NH3)zClz 'in the line y98.

The barium hydroxide precipitate is carried in the line 9,7 :to precipitation apparatus 100 whereit` isl accumulated and .then dissolved atahigh concentration bythe introduction of a small amount of hot waterfin theline 102 thereby forming Ya supply of` concentratedfbarium hydroxide solution B a(OH)2 in the line 40 for theproduction run. The copper ammonium chloride in the line 98 is recirculated through -the 'line 60 for the rst regeneration stage.

Thus the raw` materials: arethe sodium chloride .in-the line A80 andthe inexpensive calcium hydroxide `,in the line 85. The process also'furnishes ausable supplylof calciumchloride intheline 81.

'Theequations for Athe above reactions are aslollows:

:We cla-im:

l. lAA process otproducing a concentrated solution of a hydroxide of an alkali metal from a solution containing an ionizable salt of said alkali metal comprising passing a concentrated solution of a hydroxide of an alkaline earth metal selected from the group consisting of barium and strontium through a cation exchanger in the form of a resinate of said alkali metal to convert said ion exchanger into the form of a resinate of said selected alkaline earth metal and to produce as a first etliuent said concentrated alkali metal hydroxide solution; displacing said selected alkaline earth metal from said alkaline earth metal resinate to produce, as a second eifluent, a solution containing an ionizable salt of said selected alkaline earth metal and regenerating said ion exchanger back to the form of said resinate of said alkali metal by passing through said resinate at least one solution which contains said ionizable salt of said alkali metal, contacting said second eiiluent with an ionizable hydroxide capable of reacting with said ionizable salt contained in said second effluent solution to produce a solution of the hydroxide of said selected alkaline earth metal, reducing the temperature of said last mentioned hydroxide solution produced thereby until said alkaline earth metal hydroxide is precipitated out of said solution, dissolving said precipitated alkaline earth metal hydroxide in a sufficient volume of water and at a suiciently high temperature to produce said alkaline earth metal hydroxide in a concentrated solution and thereafter passing said concentrated solution through said regenerated resinate of said alkali metal.

2. The process of claim l wherein said displacement of said selected alkaline earth metal from ysaid alkaline earth metal resinate ion exchanger and said regeneration of said ion exchanger are carried out sequentially in a plurality of ion exchange runs which include passing through said alkaline earth metal resinate ion exchanger a solution containing an ionizable salt of a metal other than said alkali metal to produce said second efliuent thereby converting said exchanger to a resinate of said other metal, and passing through said last mentioned resinate a solution containing said ionizable salt of said alkali metal to produce said regenerated resinate exchanger.

3. The process of claim l wherein said selected alkaline earth metal is displaced from said alkaline earth metal ion exchanger to produce said second etiiuent, and said ion exchanger is also regenerated to said alkali metal resinate ion exchanger simultaneously, by passing said solution of said ionizable salt of said alkali metal through said alkaline earth metal resinate ion exchanger.

4. A process of producing a concentrated sodium hydroxide solution from a sodium chloride solution which comprises passing a concentrated solution of a hydroxide of an alkaline earth metal selected from the group consisting of barium and strontium through a sodium resinate ion exchanger producing as a rst eiiuent said concentrated sodium hydroxide solution and converting said sodium resinate ion exchanger to a resinate of said selected alkaline earth metal; thereafter passing said solution of sodium chloride through said alkaline earth metal resinate to produce as a second eiliuent a chloride of said selected alkaline earth metal and to regenerate said alkaline earth metal resinate into said alkali metal resinate, contacting said second eiuent with an ionizable hydroxide capable of reacting with said alkaline earth metal chloride contained in said second eliiuent solution to produce a solution of said alkaline earth metal hydroxide, reducing the temperature of said last mentioned hydroxide solution formed thereby until said alkaline earth metal hydroxide is precipitated out of said solution, dissolving said precipitated hydroxide in a sucient volume of water and at a suiciently high temperature to produce said alkaline earth metal hydroxide in a concentrated solution and thereafter passing said concentrated solution through said regenerated resinate of said alkali metal.

5. The process of claim 4 wherein said ionizable hydroxide comprises a metal ammonium hydroxide.

6. The process of claim 4 wherein said ionizable hydroxide comprises a copper ammonium hydroxide` 7. The process of producing a concentrated sodium hydroxide solution from a sodium chloride solution which comprises passing a concentrated solution of a hydroxide of an alkaline earth metal selected from the group consisting of barium and strontium through a sodium resinate ion exchanger and producing, as a first effluent, said concentrated sodium hydroxide solution and converting said sodium resinate into a resinate of said selected alkaline earth metal, passing through said alkaline earth metal resinate ion exchanger a solution containing an ionizable chloride salt of a metal other than sodium to produce as a second eiiluent a solution of a chloride of said selected alkaline earth metal and thereby converting said exchanger to a resinate of said other metal, passing through said converted resinate exchanger a solution containing calcium chloride to convert said exchanger to a calcium resinate, and passing through said calcium resinate a solution containing said sodium chloride to regenerate said exchanger to a sodium resinate, contacting said second eifluent with an ionizable hydroxide capable of reacting with said chloride of said selected alkaline earth metal contained in said second eliiuent solution to produce a solution of the hydroxide of said selected alkaline earth metal, reducing the temperature of said last mentioned hydroxide solution produced thereby until said alkaline earth metal hydroxide is precipitated out of said solution, dissolving said precipitated alkaline earth metal hydroxide in a suiiicient volume of water and at a suiciently high temperature to produce said alkaline earth metal hydroxide in a concentrated solution and thereafter passing said concentrated solution through said regenerated sodium resinate exchanger.

8. The process of claim 7 wherein said solution containing said ionizable chloride salt of said metal other than sodium comprises a metal ammonium chloride solution, said resulting resinate is a metal ammonium resinate and said ionizable hydroxide comprises a metal ammonium hydroxide.

9. The process of claim 8 wherein said metal ammonium chloride, said metal ammonium resinate and said metal ammonium hydroxide comprises respectively copper ammonium chloride, copper ammonium resinate and copper ammonium hydroxide.

References Cited in the file of this patent UNITED STATES PATENTS 720,927 Jacobs Feb. 17, 1903 960,887 Gans lune 7, l9l0 974,993 Rollins Nov. 8, 1910 1,799,989 Rusberg Apr. 7, 1931 2,409,861 Hunter et al. Oct. 22, 1946 2,606,098 Bauman Aug. 5, 1952 OTHER REFERENCES Kumin and'Myers Ion Exchange Resins, 1950 Ed., pages 3l, 32, 76-82, 89. John Wiley & Sons, Inc., N. Y. 

1. A PROCESS OF PRODUCING A CONCENTRATED SOLUTION OF A HYDROXIDE OF AN ALKALI METAL FROM A SOLUTION CONTAINING AN IONIZABLE SALT OF SAID ALKALI METAL COMPRISING PASSING A CONCENTRATED SOLUTION OF A HYDROXIDE OF AN ALKALINE EARTH METAL SELECTED FROM THE GROUP CONSISTING OF BARIUM AND STRONTIUM THROUGH A CATION EXCHANGER IN THE FORM OF A RESINATE OF SAID ALKALI METAL TO CONVERT SAID ION EXCHANGER INTO THE FORM OF A RESINATE OF SAID SELECTED ALKALINE EARTH METAL AND TO PRODUCE AS A FIRST EFFLUENT SAID CONCENTRATED ALKALI METAL HYDROXIDE SOLUTION; DISPLACING SAID SELECTED ALKALINE EARTH METAL FROM SAID ALKALINE EARTH METAL RESINATE TO PRODUCE, AS A SECOND EFFLUENT, A SOLUTION CONTAINING AN IONIZABLE SALT OF SAID SELECTED ALKALINE EARTH METAL AND REGENERATING SAID ION EXCHANGER BACK TO THE FORM OF SAID RESINATE OF SAID ALKALI METAL BY PASSING THROUGH SAID RESINATE AT LEAST ONE SOLUTION WHICH CONTAINS SAID IONIZABLE SALT OF SAID ALKALI METAL, CONTACTING SAID SECOND EFFLUENT WITH AN IONIZABLE HYDROXIDE CAPABLE OF REACTING WITH SAID IONIZABLE SALT CONTAINED IN SAID SECOND EFFLUENT SOLUTION TO PRODUCE A SOLUTION OF THE HYDROXIDE OF SAID SELECTED ALKALINE EARTH METAL, REDUCING THE TEMPERATURE OF SAID LAST MENTIONED HYDROXIDE SOLUTION PRODUCED THEREBY UNTIL SAID ALKALINE EARTH METAL HYDROXIDE IS PRECIPITATED OUT OF SAID SOLUTION, DISSOLVING SAID PRECIPITATED ALKALINE EARTH METAL HYDROXIDE IN A SUFFICIENT VOLUME OF WATER AND AT A SUFFICIENTLY HIGH TEMPERATURE TO PRODUCE SAID ALKALINE EARTH METAL HYDROXIDE IN A CONCENTRATED SOLUTION AND THEREAFTER PASSING SAID CONCENTRATED SOLUTION THROUGH SAID REGENERATED RESINATE OF SAID ALKALI METAL. 